Melanoma - Skin Cancer: Skin Health

Content provided by the Faculty of the Harvard Medical School

Melanoma

Melanoma is a form of cancer that originates in the melanocytes, cells deep in the epidermis or in surface moles that produce pigment. Each year, malignant melanoma is diagnosed in about 45,000 Americans. Although it accounts for only 4% of cases of skin cancer, it's responsible for more than 75% of all skin cancer deaths. Without early detection and treatment, it can spread (metastasize) to the lymph nodes and internal organs. The lungs and liver are common targets when melanoma spreads. Its incidence has risen dramatically, from 1 in 5,000 in 1930, to about 1 in 65 in 2004.

Melanoma has several distinguishing characteristics that experts call the ABCDs of melanoma. These are asymmetry, meaning that each half of the growth looks different from the other; border irregularity, in which the edges are ragged or blurry; color that's unusual; and a diameter that exceeds 6 mm, about that of a pencil eraser. In general, experts recommend that any mole or growth that has enlarged or changed in any way be examined by a dermatologist.

Treating melanoma

If a growth or mole looks like a melanoma, the doctor will take a biopsy to confirm the diagnosis. This entails removing either a sample of tissue or else the entire growth and some surrounding skin, and examining the tissue under a microscope to determine whether it's cancer. Depending on how deep a melanoma is, further tissue may have to be removed. In some cases, lymph nodes may be removed, too. A procedure called sentinel node biopsy is becoming more common to determine if the lymph node nearest the tumor contains any cancer cells. If it does, surgery to remove additional nodes right away can improve survival, according to a study published in 2006 in the New England Journal of Medicine.

In addition to surgery, standard treatments for melanoma include chemotherapy, radiation therapy, and biological therapy, which strengthens the immune system against the cancer. For reasons still not understood, chemotherapy generally helps only a small number of people with melanoma, and there is no standard treatment regimen.

Melanoma survival rates are good — 95% or higher if the tumor is less than 1 mm thick. But beyond 4 mm in thickness, the cure rate drops to 45%. As with most other forms of cancer, if the tumor has spread to distant organs, overall survival is lower, about 18%.

Last updated:	July 20, 2007